The present invention relates to a clamp coupling that connects a plurality of objects to be connected with each other by holding the connecting objects in a circular groove and also to a method of fastening the clamp coupling.
In a diesel particulate filter (hereinafter referred to as DPF) for purifying exhaust gas discharged from a diesel engine, oil-derived calcium compound substance is deposited in the filter. In order to maintain the desired purifying performance of the DPF, it needs to be cleaned for refreshment. Japanese Patent Application Publication No. 2003-120277 discloses a device for purifying exhaust gas from an internal combustion engine. The DPF which is accommodated in a cylindrical case needs to be removed therefrom for cleaning of the DPF. For this purpose, the cylindrical case is configured to include two halves that are separable from each other. Each cylindrical case half has a circular flange portion and the cylindrical case halves are connected together at the flange portions thereof by a clamp coupling. The clamp coupling includes circular clamp segments each having therein a groove of U or V section. The clamp segments extend around the cylindrical case while holding therebetween the flange portions in the grooves.
The clamp coupling should preferably be reused after the clamp coupling is removed. However, there are problems in reusing the clamp coupling. The clamp segments of the clamp coupling are made of spring steel. The clamp segments having therebetween the flange portions of the cylindrical case exert the spring force in a direction that holds the flange portions. If the clamp coupling holding the flange portions of the cylindrical cases is exposed to heat of exhaust gas through the cylindrical cases, creep occurs in the clamp coupling, so that spring force of the clamp segments is reduced and such insufficient spring force renders the clamp coupling inappropriate for reuse.
The present invention which has been made in light of the problems mentioned above is directed to providing a clamp coupling to connect a plurality of objects to be connected with each other. The clamp coupling has a plurality of clamp segments having the connecting objects held therebetween and disposed in a manner that may shorten the circumferential length thereof so as to ensure a spring force that is required for connecting the plural objects even after creep occurs in the clamp segments.